PLANT FOSSIL ATLAS from (Pennsylvanian) CARBONIFEROUS AGE FOUND in Central Appalachian Coalfields
153 pages
English

PLANT FOSSIL ATLAS from (Pennsylvanian) CARBONIFEROUS AGE FOUND in Central Appalachian Coalfields , livre ebook

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153 pages
English
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Description

This book is a picture guide to fossil plants and a few fossil marine organisms found in close association with the coal measures in the central Appalachian region. The fossils are sorted by groups and the specimens sampling site locations are listed by coal seam horizon and geographic location. Short descriptions of each group of fossil types are provided. This publication has been designed with the amateur (rock hound) as well as a virtual guide for the more advanced collectors. Explanation of the different groups of plants in as close to layman’s terms as possible.


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Publié par
Date de parution 08 septembre 2017
Nombre de lectures 0
EAN13 9781947938021
Langue English
Poids de l'ouvrage 8 Mo

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PLANT FOSSIL ATLAS from (Pennsylvanian) CARBONIFEROUS AGE FOUND in Central Appalachian Coalfields
Thomas F. McLoughlin
Geologist, M.S.


Copyright © 2017 by Thomas F. McLoughlin.

Paperback: 978-1-947938-01-4
eBook: 978-1-947938-02-1


All rights reserved. No part of this publication may be reproduced, distributed, or transmitted in any form or by any electronic or mechanical means, without the prior written permission of the publisher, except in the case of brief quotations embodied in critical reviews and certain other noncommercial uses permitted by copyright law.


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Table of Contents
Acknowledgement
Foreword
Introduction
Collecting Plant Fossils
Chapter 1
ARBORESCENT LYCOPODS (CLUB MOSSES, SCALE TREES)
Lepidodendron
Chapter 2
ARBORESCENT LYCOPODS (CLUB MOSSES)
Sigillaria
Chapter 3
CORDAITES: EARLY GYMNOSPERMS
Ancient Mangrove-Like Plant
Chapter 4
KETTLEBOTTOMS
Ancient Tree Trunks
Chapter 5
STIGMARIA
Ancient Root Systems
Chapter 6
CALAMITES
Ancient Relative of the “Horsetail”
Chapter 7
SPHENOPHYLLUM
Chapter 8
FERNS
Chapter 9
SEEDS
Chapter 10
MARINE FOSSIL FAUNA
FOUND WITH PLANT FOSSIL FLORA
References
Appendix A



Pennsylvanian coal swamp vegetation reconstruction, a composite of many plant types growing in and around the swamp (Kukuk, 1938).


Acknowledgement
T his book could not have been completed without the dedicated help of Cortland F. Eble, Ph.D., and Alton Dooley, who are paleontologists with the Kentucky Geological Survey in Lexington, Kentucky, and the Museum of Natural History in Martinsville, Virginia, respectively. They helped edit the manuscript. Assistance in the classification of many of the fern fossils was given by Dr. Shusheng Hu, who is a paleobotanist and Collections Manager, Division of Paleobotany at the Yale Peabody Museum of Natural History in New Haven, Connecticut.
I also want to thank my wife, Beth, for her patience and tolerance for the numerous boxes of fossil specimens in our home. She was very relieved when I donated the collection to the Museum of Natural History.
All of the fossils listed in the plates were collected by and photographed by the author except as noted.


Foreword
I have spent the last twenty-seven-plus years in and around the bituminous coal mines of southwestern Virginia. When coal miners learn I am a geologist, the most popular question has been “what are the kinds of fossils we see in a mine roof?” I give my best reply, but it is difficult to relate to them that the plant impressions represent vegetation that grew in peat-forming swamps millions of years ago. Most people recognize the fern-like fossils, but have been confused about the identity of a portion of tree root versus the tree itself. Many believe that the fossils are not those of ancient vegetation, but instead are the preserved remains of fish or reptiles.
I became interested in geology because of these fossils. It is the goal of this publication to share my accumulated experience in the area of basic paleobotany and furnish a pictorial guide to the identification of the more common Carboniferous-age plant fossils from the coal fields of Virginia. Those especially targeted are the rock hounds and aspiring geologists of all ages.
In 1977, I received my Bachelor of science degree from Morehead State University (MSU) in Morehead, Kentucky. In the spring of 1980, I graduated from Eastern Kentucky University (EKU) in Richmond, Kentucky, with a Master of science degree in geology.
During those years, the majority of my geologic experiences centered on the geologic aspects of underground coal mine roof stability by benefit of U.S. Bureau of Mines contracts awarded to a professor at MSU, Dr. David K. Hylbert. I owe a large part of my success as a geologist to Dr. Hylbert; Dr. Harry Hoge, my thesis adviser at EKU; and Dr. Jules DuBar, my paleontology professor while I was at MSU. Therefore, I wish to dedicate this publication to them as thanks for their guidance and inspiration.


Introduction
F ossils have excited people for a long time, but for about 400 years, the term was used to describe almost anything that looked like it had organic origins and was dug up from the earth. “Fossil” is defined by paleontologists as any object that represents the presence of a former life, as the term also applies to the preservation of various trace fossils such as animal trackways and coprolites (fecal pellets). By convention, use of the term is generally restricted to remains that are older than 10,000 years.
The study of fossilized plant remains is called paleobotany. Understanding how plants inhabited the earth throughout geologic time allows the paleobotanist to begin to piece together the history of the plant kingdom. Fossil plants come in a variety of shapes and sizes that vary throughout geologic time. Examining and identifying species that lived millions of years ago allows us to glimpse into ecological, and therefore, evolutionary occurrences. Generally, the preservation of an organism requires a rapid burial in sediment, usually clay (mud), silt, or fine grained sand, before the soft body portions completely decay or are fragmented to such an extent that it cannot be identified as a specific type of organism. Even after preservation, few fossils are discovered and collected before weathering and erosion destroy the rocks that carry them.
Fossil plants can be preserved in a variety of ways. Most commonly, the shape of the plant is impressed into the sediment. During this process, plant material falls into the water, becomes water-logged, sinks to the bottom of the body of water, and becomes surrounded and covered by sediments. Slowly, under the increasing weight of the additional sediments, water and air are pressed out until only plant material remains. The flattened plant part appears as a fossil compression on one layer of the strata, while the other side contains the impressed counterpart or “impression.”
Frequently root systems, trunks, and limbs in the proper growing position of plants become engulfed by sediments during floods when streams and rivers overflow their banks or shift their courses. Sediment partially or completely replaces decaying plant (organic) material so that the walls of the resulting cavity (or mold) form with exact details. Standing tree or trunk casts that were buried in this fashion are called “kettle bottoms” or “stove pipes” by the mining industry because of the flared or bowl shape at the base and upward taper.
Often as the depth of burial increases, heat and pressure builds causing the gradual loss of original organic tissue to the extent that only a layer of carbonaceous material (coal) remains, a process known as carbonization. Often these fossils are the most spectacular and “pretty,” since even the most delicate details of leaves, barks of trees, and branches are preserved in an almost life-like fashion. Veins and filaments stand out in stark relief in these fossil examples. This is the typical type of preservation found in coal seams.
If the tree became buried in sediment and water percolated through the ground, then each individual cell of the organism might be replaced by dissolved minerals including silica (quartz or jasper), calcium carbonate (calcite), or iron magnesium carbonate (ironstone). This would result in petrifaction of the organism.
The Appalachian region of the United States is full of plant fossils that represent a thriving ecosystem during the Carboniferous period (360 to 286 million years ago); this guide focuses on the most wide-spread and commonly found flora of that period. Unique water chemistry and a tropical climate created extensive coal swamps in the Appalachian Mountains; under these conditions it is very rare to find the hard parts of animals because they were not preserved well. Some shell fossils of brackish water to shallow marine brachiopods are sometimes locally abundant in certain rock units (e.g., the Magoffin Beds in the Wise Formation) in the tristate region (Virginia, West Virginia, and Kentucky). A few brachiopods, pelecyepods, and nautiloids associated with the plant fossils were also collected, but these are very small and easily overlooked by the untrained eye. Even though there are numerous plant fossils to be found, these most likely represent only a small fraction of the abundant flora that existed because plants are so susceptible to decay.
The majority of the specimens pictured in this publication were collected from coal mines in southwestern Virginia. Of the numerous coal seams that are mined in Virginia, there are a few that had special conditions conducive to optimum preservation. These include the Jawbone, Lower Banner, Upper Banner, Splashdam, Kennedy, Hagy, and Taggart seams; all of these seams are Pennsylvanian in age (a standard geologic time scale is shown in figure 1). The locations of the collection sites are listed in Appendix A.
Throughout, there are comparisons made between fossil and present-day plants to aid in the interpretation of structures observed in the extinct plants. Several plants found living today are also preserved as fossils and show few little changes in morphology (appearance). Most notable is the group of extinct plants called Calamites; the modern horsetail is closely related to Calamites, but horsetails are much smaller in size. Because of this, the horsetail is often referred to as a “living fossil.”
A most notable collecting site is one located just west of Coeburn, Virginia, along the westbound stretch of U.S. Route 58 Alternate. The section represents an ancient volcanic ash bed as evidenced by an unusually high amount of the clay mineral montmorillonite, which is known to be a weathering product of volcanic ash. The clay is also mixed in with the sandstone. Together with the sandstone and clay, there are layers of rock at least 50 feet in thickness. Specimens of Lepidodendron , Sigillaria , Calamites , seed ferns Neuropteris and Alethopteris , pollen organs Whittleseya , and a seed pod Holcosper mum were found at this location near Coeburn in Wise County, Virginia, immediately above the Aily coal seam.

Figure 1. General geologic time scale showing the various coal seams from which fossils were collected. Also see Appendix A for names of the formations and coal seams in which the fossils were found.

Figure 2. Index map of the study area where Fossil flora and fana have been collected from southwestern Virginia and southwestern, West Virginia. Appendix A list the more detailed description of the precise location of the fossil collection sites.


Collecting Pl ant Fossils
T o the beginner, finding plant fossils or fossils in general can be frustrating. Often the first time out or even the second may not be productive. However, I have learned that perseverance and patience will win out. There is also a certain degree of luck involved.
You need to get permission from the landowner before you enter and collect. Do not cross locked gates or posted “No Trespassing” signs. Although it may be tempting, abandoned coal mines are always prohibited from entry.
The basic tools required for successful collecting are as follows: (1) A masons’ hammer—one with a chisel (wide blade) end, (2) a handheld rock splitter for larger rocks, (3) gloves, (4) safety goggles or other eye protection, (5) safety shoes or hard-toe boots, and (6) a hard hat (see figure 3). Always wear a hard hat and proper footwear to protect you from falling debris. Remember safety first. Lists of fossil-collecting localities are generally not published. In planning a field trip, you can find your own sites by learning to use geologic and topographic quadrangle maps for your area. They contain an abundance of information useful to the collector.
Plant fossils are usually found at or immediately above a coal seam. Once you find one, first conduct a quick survey of the talus (i.e., weathered material—fragments of rock that accumulate at the base of an outcrop or road cuts).
Once a locality proves to have the potential for bearing fossils, it is time to start breaking rocks. Remember to don your safety equipment before commencing the hunt. This is where patience is required because it will require the splitting and resplitting of many rocks before the fruits of your labor are realized. In fact, many times the strata will be so deeply weathered that only fragments of what would otherwise have been a whole specimen come out as small pieces or crumble in your hands. Thus some digging is required to get to the firmer rock. Often it is necessary to migrate laterally and vertically in the outcrop to find a horizon that is fossil bearing. Based on experience, the best advice is to follow the fossils. Just like in the movie The Wizard of Oz , once on the “yellow brick road,” one continues upward from the talus in search of the source of the specimen. Also, be alert to the encounter of marine-type fossils such as snails and clams, as described earlier in the introduction. You may discover a fossil which may have eluded the trained eye of the professional geologist.
In transporting the specimens home, be sure to take precautions against the potentially damaging effects of excessive vibration in a vehicle. Be sure to use plenty of padding regardless of the size and firmness of the rock. After arriving home, the next step is to clean your specimens. Use a very fine and soft hairbrush (most recommended is one made of camels’ hair) to clear away loose debris. Ask your dentist for instruments that are to be discarded; inform him that they make excellent tools for breaking away thin surface layers of rock to more fully expose plant fossils.
Next, photograph your prizes to share with others (some even make great wallpaper for a computer screen). Should the contrast be very small between the color of the fossil and its matrix, a very thin coating of polyurethane may be required to bring out the full beauty of the specimen. This process will also retard the rate of decay of the rock and protect against any major damage to the fossil. Most are preserved in a thin film of carbon, which may flake and peel over time, especially when handled frequently.
Using either acrylic paint or correction fluid, make a large enough area to document the location from which the sample was collected. Someone else may want to visit the site in the hopes of finding their own. An identification card with additional information is often included in the same container or place in which you store or display the fossil.
Identification of the fossils with specific names or classifications takes a lot of practice. The best way to start is to go to a library and find reference books. Most have photographs and drawings of the most common plant fossils that you can compare with your own. To help verify the name of the fossil, read the descriptions offered by the books. Conferring with a geologist (and better, a paleontologist) is usually needed for identifying the genus and species. Browsing the Internet (as I did) can also offer very valuable information.

Figure 3. Safety equipment and tools for collecting fossils. The camel-hair brush and old dentist’s tools are used to clean and dress the fossils in preparation for a protective sealant and photographing.


Chapter 1
ARBORESCENT LYCOPODS (CLUB MOSSES, SCALE TREES)
Lepidodendron
L epidodendron . This plant is sometimes referred to as a “scale tree” because of the distinctive teardrop or diamond-shaped pattern of the bark of this lycopod. It is often mistaken for the scales of a reptile or a snake’s skin. Each scale-like feature is accented by a small depression that looks like an eye.

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